Making a Bee Hotel from Natural Materials

Why solitary bees deserve a place in your garden

Of the roughly 270 bee species recorded in Britain, the great majority are solitary. They do not live in colonies, they do not make honey, and they have no queen. Each female works alone, building a series of individual nest cells, stocking each one with pollen and nectar, laying an egg, and sealing it up before moving on. Around seven in ten of these bees nest underground, but a good number — including the familiar red mason bee and the leafcutter bee — nest in hollow plant stems and old beetle holes in dead wood. In a tidy, well-swept garden those cavities are in desperately short supply.

The good news is that a bee hotel is one of the cheapest and most rewarding wildlife projects you can take on. Built properly, from natural materials, it will be used within a season. Built carelessly, it becomes a trap. The difference comes down to a few details: the right depth, the right diameter, a dry position in full sun, and a willingness to leave it alone once it is occupied.

Pick the spot before you pick up a drill

Placement matters more than craftsmanship. Solitary bees need warmth to become active in the morning, so face your hotel somewhere between south-east and south-west, where it will catch the sun for most of the day. Fix it at least a metre above the ground — 1.5 to 2 metres is ideal — and make sure it is firmly mounted so it does not sway or rattle.

Rain is the real enemy. A nesting tunnel that stays damp will grow mould, and mould kills the larvae inside. Choose a position that is sheltered from the prevailing wind and, if you can, tucked under a slight overhang: a south-facing wall, a garage gable, or beneath the eaves of a shed all work well. A metre or so of clear air in front of the entrance helps too, so the bees have a clean flight path in and out.

Drilling a timber block

A solid block of untreated timber is the most durable option and the easiest to get right. Use hardwood or softwood offcuts — oak, ash, beech, or a section of untreated fence post. Avoid anything that has been pressure-treated, stained, varnished or painted, as the chemicals can harm developing larvae.

A block roughly 100mm square and 150mm deep will give you plenty of nesting tunnels. Then work through it carefully:

• Diameter: drill holes between 2mm and 10mm. An 8mm bit suits red mason bees, 6mm suits leafcutters, and the smaller 2–4mm holes will attract tiny species that most gardeners never notice.
• Depth: drill to 100–150mm, but never right through. The tunnel must have a closed end.
• Spacing: leave 15–20mm of solid timber between holes so the walls do not split.
• Finish: sand the face flat so bees are not tempted to nest in a splintered entrance, and blow or brush out every trace of sawdust.
• Angle: mount the block with a very slight downward tilt so rainwater runs off rather than in.

Bundling hollow stems

Stem bundles feel more natural and are quick to make, though they need replacing more often. Collect bamboo canes, bramble, teasel, hogweed, elder, or last year's sunflower stalks. Cut them into lengths of about 150mm using clean secateurs or a fine saw.

Bramble and elder have a soft pith inside that bees cannot use, so push it out with a length of stiff wire. Wherever possible, cut just below a node, which gives you a naturally sealed end. Then pack the stems tightly into a holder — an old tin can with the label removed, a short length of drainpipe, or a plastic bottle with both ends cut off. Push them in so the open ends sit slightly proud of the rim, and mount the whole thing at the same gentle downward angle as the timber block. Pack them tightly enough that they cannot shift; loose stems wobble, and a wobbly tunnel gets abandoned.

What to leave out

Some materials sold as bee hotels do more harm than good. Steer clear of the following:

• Plastic drinking straws: they trap condensation, and the smooth surface offers no grip for emerging bees.
• Glass or clear plastic tubes: light encourages algae growth inside the tunnel.
• Treated or painted timber: the preservatives are toxic to larvae.
• Holes drilled into end grain: softwood end grain splinters badly and the tunnels collapse.
• Large boxes of mixed sizes with no thought behind them: a small, well-made block in the right spot beats a big decorative one every time.

Looking after your guests

The hardest part of keeping a bee hotel is leaving it alone. Once tunnels are sealed, the bees inside are developing through the summer and will overwinter as dormant larvae or cocoons. Do not move the hotel, and do not clean it out, before the following spring — emerging bees need to find their way out of the same entrance they were laid in.

Come September or October, once all the adults have flown, you can tidy up. Take the stem bundles apart, discard any that are cracked or damp, and replace them with fresh ones. With a solid timber block, use a bottle brush or a stiff piece of wire to clear out old nesting debris, then leave it to dry somewhere cool before remounting. Clean tunnels are far less likely to harbour parasites and fungal disease.

Do that much and you will have a hotel that fills year after year — and a garden that quietly does its bit for some of our most hard-working, least celebrated insects.